This invention relates in general to electrical testing equipment and more particularly to a hand-held tester for checking the operativeness of a ground fault interrupter in an electrical outlet.
The National Electrical Code now requires ground fault interrupter protection for newly-installed residential outdoor, kitchen and bathroom outlets, in addition to outlets near swimming pools on construction sites and elsewhere. Assuring proper operation of newly-installed interrupter is necessary to avoid building code violations and costly repairs at a later time. Similarly, proper interrupter operation on construction sites is important to job progress and woker safety. Insensitive devices fail to protect users while hypersensitive ones break circuits due to non-dangerous conditions such as line transients and motor starts. The latter problem is called nuisance tripping. Dirty outlets tend to become hypersensitive making nuisance tripping a common problem.
In the past, testing of a ground fault interrupters has been accomplished with go or no-go type devices. These devices would create a single test condition to which the interrupter might or might not react. In either case, the person doing the testing lacks full information because he does not know the condition impressed on the interrupter during the test. If the interrupter did not trip, it could be that the device properly failed to respond to a low-level ground fault. It could also be that the trip mechanism is not functioning. On the other hand, if the interrupter does trip after application of a go/no-go tester, there is still no assurance that the interrupter is not subject to nuisance tripping.